Q: We live in the south and have a zoysia grass lawn. It feels spongy when we walk on it. We have been told that thatch is growing. It costs a lot to dethatch a lawn. Is it very harmful to the lawn? Is there a less expensive way to get rid of it?

A: Thatch is made up of above-ground roots and stems of a grass plant. It is not the tan-colored grass blades left over from mowing; it looks like a mass of threads that are usually dark-brown color.

The roots and stems should mostly grow down in the soil, but for some reason they're growing on the soil. As thatch gets thicker, it prevents water from reaching the soil. Grass roots can't grow in the soil without water, so they die, leaving only the roots growing in the thatch. A half-inch or less of thatch is normally fine, but if the lawn feels spongy to walk on I would guess the thatch layer on your lawn is over an inch thick. In this case, a single dethatching will not fix your lawn; you need a long-term strategy.

Thatch control is often done when grass will actively grow and fill in the bare spots. Northern cool-season grasses are dethatched in the fall, and warm-season grasses (like your zoysia) should be dethatched now, between June and July. Since the grass leaves and crown (the base of the plant) are growing on top of the thatch, dethatching will undoubtedly ruin the appearance of your lawn.

As part of your strategy, you need to figure out what is causing the thatch to grow. Is the soil compacted? Is the soil pH level too high or low? Does the lawn flood? Does the irrigation system run too long, drowning the grass roots trying to grow in the soil? Some varieties of grass, like your zoysia, grow more thatch than others.

One thing to do is reduce the amount of nitrogen fertilizer on your lawn. You may apply too much by following a four-step lawn-fertilization program. Then, water the lawn deeply, and then not again for a week or ten days. Do not lightly water the lawn because a small amount of water won't penetrate deep into the soil, and the roots will only grow near or on the surface.

If the layer of thatch is less than an inch thick, core aeration (removing soil cores with a soil aerator) is the best first step to reduce it. The cores must be removed every 2 to 3 inches in both directions, which may require several passes over the lawn with the aerator. The deeper the hole the better. After aerating the lawn, spread a thin layer of compost. The decay organisms in the compost will help decay the dead organic material in the thatch. Compost will also help with soil problems if it gets into the core holes. You will need to aerate the lawn several times over the next few years.

Using a power rake to remove thatch is another approach, but it will remove your lawn completely. Only do this if you want to replace the grass with another kind.

Q: Part of our vegetable garden flooded. The plants are starting to recover. Do you think it is safe to eat the produce?

A: Don't consume any produce that has been underwater if there is any chance the floodwater is contaminated with animal manure or sewage. I would throw out any discolored fruit. New fruit that grows on the plants should be fine, although I would replace any leafy green crops no matter what. If any of the new crops grow on or close to the ground, I would place newspapers or plastic under the fruit so it doesn't touch the ground.

Email questions to Jeff Rugg at info@greenerview.com. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.